Don't forget, these Leader skills are also supposed to buff your BOffs on away missions. Granted, if all you're interested in is space combat then that's no consolation.
I don't think it does this, even though it says it does.
E.G. Tactical Team is supposed to increase the Close Combat and Assault skills of your away team... But your away team officers do not have a Close Combat or Assault skills (unless they are another player). But at any rate, investing skills in Close Combat (as a tactical officer) increases your melee damage. So, if I am investing skills in Tactical Team, which supposedly increases the Close Combat skill of my Bridge Officers, then I would expect investing points in tactical team to increase the melee damage (and ranged damage) of my tactical bridge officers, but it does not. It has no influence on damage output of my tactical bridge officers whatsoever.
Furthermore, if you go to your character's skill tree and use the drop down menu to see what skill nodes will affect the combat abilities of your tactical bridge officers (e.g. Palm strike), tactical team will not be highlighted. The only thing that is highlighted is your OWN Close Combat & Martial Arts nodes (if you are a tactical captain). If you are investing points in Tactical Team with the expectation that it is improving your tactical away team members, I'm pretty sure you're just wasting points. I know that it says that Tactical Team improves such abilities, but I have seen zero change in damage output in my tactical away team officers when I have maxed out Tactical Team to rank 9 vs. if I had just left it at 0.
What I do not understand though is that maybe it has an affect if you are grouped with other players, since they DO have Close Combat and Assault nodes in their skill trees. But since I do not group with other players except very, very rarely, I can't say I've paid any attention, or can tell (since I don't have a before and after comparison).
According to the skill tree planner Tact Team Leader effect the "Strike Team" skill as well. This makes since since Engineer Team Leader effect the Engineering Proficiency skill on my VA engineer. So it may not be a waste of 700 points if you use it as a team boost. I know my group likes the +30 or defense that my Engineering Proficiency puts out for 2 minute. Real nice for boss fight at end of infected. Real nice when all three classes are able to use Strike Team, Engineer Proficiency and Scientific Aptitude just before the fight starts.
I'm 90% sure it does absolutely nothing for Tactical Team power and fairly certain it doesn't do anything for your Tactical bridge officers when on the ground. Not sure if it influences anything else for a Tactical captain on the ground, but for Engineers and Science captains it's absolutely a total waste of skill points.